Focused ultrasound systems have been suggested for delivering acoustic energy into a tissue region within a patient, such as a cancerous or benign tumor, to coagulate or otherwise treat the tissue region with thermal energy. For example, a piezoelectric transducer located outside the patient's body may be used to focus high intensity acoustic waves, such as ultrasonic waves (acoustic waves with a frequency greater than about twenty kilohertz (20 kHz)), at an internal tissue region of a patient to treat the tissue region. The acoustic waves may be used to ablate a tumor, thereby eliminating the need for invasive surgery. Such an acoustic transducer system is disclosed in U.S. Pat. No. 4,865,042 issued to Umemura et al.
When delivering acoustic energy, it is useful to control the shape of a “focal zone” (the volume of tissue treated when the acoustic energy is focused into a tissue region), to control “focal depth” (the distance from the transducer to the focal zone), and/or to correct for tissue aberrations that may be caused by intervening tissue between the transducer and the tissue region. It is also desirable to steer the acoustic energy away from a central axis of the transducer, e.g., at large steering angles relative to the central axis.
To facilitate steering acoustic energy, it is desirable to make the transducer elements as small as possible, preferably on the order of the wavelength of the acoustic energy transmitted by the transducer elements. For example, for acoustic energy having a frequency of one Megahertz (1 MHz), it would be desirable to provide transducer elements having a width or other maximum cross-section of less than one millimeter (1.0 mm). For a relatively large area transducer array, the total number of such transducer elements required would become very large, i.e., requiring hundreds or even thousands of transducer elements.
The problem with providing so many transducer elements is that individual sets of drive signals must be delivered to each transducer element in order for the transducer elements to transmit acoustic energy. Thus, hundreds or thousands of wires or cables would be required to deliver the drive signals to the transducer elements. The resulting system would be complicated and expensive to implement.
Accordingly, systems and methods for delivering acoustic energy from transducer arrays including many transducer elements would be useful.